The structure of the periodontium and its functions. Anatomical and histological structure of the pulp, functions
Department of Therapeutic Dentistry
Periodontal diseases.
Methodological guide for students, interns and residents of the dental profile.
.TOPIC: ANATOMY AND PHYSIOLOGY OF THE PERIODONT. FUNCTIONS OF THE PERIODONT.
Targets: to study the structure of all tissues that make up the periodontium, and the functions of the periodontium.
Required initial level of knowledge:
1) The structure of the mucous membrane of the gums.
2) The structure of the bone tissue of the alveoli.
3) The structure of the periodontium.
4) The structure of cement.
Questions to prepare for the lesson:
1) What is a periodontium?
2) The tissues that make up the periodontium.
3) Gingival mucosa, normal appearance of the gingival mucosa.
4) Gingival zones: marginal gingiva, alveolar gingiva, sulcular gingiva,
transitional fold.
5) Layers of the gums.
6) Histological structure of the gingival epithelium, its blood supply and innervation.
7) Histological structure of the lamina propria of the gingival mucosa, its blood supply, gingival microvasculature, plasma capillaries, innervation.
8) Gingival sulcus (sulcular gingiva), depth, histological and clinical gingival sulcus, biological gingival width: epithelial attachment, connective tissue attachment; features of blood supply and innervation.
9) Gingival fluid. Local immunity of the oral cavity (cellular and humoral, secretory immunoglobulin A).
10) Ligament apparatus of the gums.
11) Periodontium, the direction of the periodontal fibers, the shape and width of the periodontal gap. Periodontal composition: fibers, ground substance, cells (fibroblasts, cementoblasts, histiocytes, mast, plasma cells, osteoblasts, osteoclasts, epithelial cells, mesenchymal cells), blood supply, innervation.
12) Cement (primary, secondary), composition, blood supply, innervation.
13) Bone tissue of the alveoli, structure of the alveoli, lamellar bone, spongy substance, bone marrow, direction of trabeculae, bone tissue cells (osteoblasts, osteoclasts, osteocytes), blood supply, innervation.
14) Age-related changes in the periodontium.
15) Periodontal functions: trophic, support-retaining, shock-absorbing, barrier (external and internal barrier), plastic, reflex regulation of masticatory pressure.
Lesson equipment.
Table No. 71. "The structure of the periodontium."
Table No. 72
Table No. 59. "Gingival attachment."
Table No. 73. "Blood supply of the gingival papilla."
Table No. 90. "The structure of the bone tissue of the interdental septa of the lateral teeth."
Table No. 100. "The structure of the bone tissue of the interdental septa of the front teeth."
PERIODONT- This is a complex of tissues surrounding the tooth, constituting a single whole, having a genetic and functional commonality.
The term "periodontium" comes from the Greek words: para - around, about; and odontos - tooth.
Tissues that make up the periodontium:
gum,
bone tissue of the alveoli (together with the periosteum),
periodontium,
tooth (cement, root dentin, pulp).
GUM- mucous membrane covering the alveolar processes of the jaws and covering the necks of the teeth. Fine the mucous membrane of the gums is pale pink in color, its surface is uneven, similar to an orange peel (the so-called "steepling") due to small retractions that form at the site of attachment of the gums to the alveolar bone by bundles of collagen fibers. With inflammatory edema, the irregularities of the mucous membrane of the gums disappear, the gum becomes even, smooth, shiny.
gum zones:
marginal gingiva, or free gingival margin;
alveolar gum, or attached gum;
sulcular gum, or gingival sulcus;
transitional fold.
Alveolar gum- gum covering the alveolar process of the jaws, 1-9 mm wide.
Sulcular gingiva(gingival sulcus) - a wedge-shaped space between the surface of the tooth and the marginal gum, a depth of 0.5-0.7 mm.
gingival sulcus lined with striated epithelium, which is attached to the enamel cuticle. The place where the epithelium attaches to the enamel is called gingival attachment. Gingival attachment is considered as a functional unit, consisting of 2 parts:
epithelial attachment, or junctional epithelium, which forms the bottom of the gingival sulcus, is found above the enamel-cement junction on the enamel. The width of the epithelial attachment ranges from 0.71 to 1.35 mm (average -1 mm);
connective tissue fibrous attachment, which is at the level of the enamel-cement joint on the cement. The width of the connective tissue attachment ranges from 1.0 to 1.7 mm (average 1 mm).
Depth anatomical gingival sulcus less than 0.5 mm, determined only histologically.
Clinical gingival sulcus a depth of 1-2 mm is determined by probing.
The epithelial attachment is weak and can be destroyed by probing or working with other instruments. For this reason, the clinical depth of the gingival sulcus is greater than the anatomical depth. Disruption of the connection between the attachment epithelium and the enamel cuticle indicates the beginning of the formation of a periodontal pocket.
Histological structure of the gums.
Histologically, the gum consists of 2 layers:
stratified squamous epithelium,
own plate of the mucous membrane of the gums (lamina propria).
The structure of the stratified squamous epithelium of the oral cavity:
basal layer- consists of cylindrical cells located on the basement membrane;
spiny layer- consists of polygonal-shaped cells, which are interconnected using hemidesmosomes;
granular layer– cells are flat, contain grains of keratohyalin;
stratum corneum- cells are flat, without nuclei, keratinized, constantly desquamated.
In the cytoplasm of cells of all layers of the epithelium (except for the stratum corneum) there are a large number of tonofilaments. They define turgor gums, which resists the mechanical load on the mucous membrane and determines its extensibility. With age, the number of tonofilaments increases by 3 times. The epithelium of the marginal gingiva keratinizing, which makes it more resistant to mechanical, temperature and chemical influences during meals.
Between the cells of the stratified squamous epithelium is an adhesive ground substance connective tissue (matrix), which includes glycosaminoglycans(including hyaluronic acid). Hyaluronidase(microbial and tissue) causes depolymerization glycosaminoglycans the main substance of the connective tissue, destroying the bond of hyaluronic acid with the protein, the hyaluronic acid molecule changes its spatial configuration, as a result of which the pores increase, and the permeability of the connective tissue for various substances, including microbes and their toxins, increases.
Histological structure of the attachment epithelium.
The epithelium of the attachment consists of several (15-20) rows of oblong cells located parallel to the surface of the tooth. There are no blood vessels and nerve endings in the epithelium of the gingival mucosa.
Histological structure of the lamina propria of the gingival mucosa.
own record is a connective tissue formation, consists of two layers:
superficial (papillary),
deep (mesh).
mesh layer formed by denser connective tissue (contains more fibers).
Connective tissue composition:
ground substance- intercellular matrix (35%), formed by macromolecules of proteoglycans and glycoproteins. The main glycoprotein is fibronectin, which provides the connection of the protein with the cellular matrix. Another type of glycoprotein laminin- provides attachment of epithelial cells to the basement membrane.
fibers(collagen, argyrophilic) - 60-65%. Fibers are synthesized by fibroblasts.
cells(5%) - fibroblasts, polymorphonuclear leukocytes, lymphocytes, macrophages, plasma cells, mast cells, epithelial cells.
The gums are supplied with blood from the subperiosteal vessels, which are the terminal branches of the hyoid, mental, facial, great palatine, infraorbital and posterior superior dental arteries. There are many anastomoses through the periosteum with the vessels of the alveolar bone and periodontium.
Microcirculatory bed gums are represented by: arteries, arterioles, precapillaries, capillaries, postcapillaries, venules, veins, arterio-venular anastomoses.
Features of the capillaries of the mucous membrane of the gums.
The capillaries of the gingival mucosa are characterized by:
the presence of a continuous basement membrane,
the presence of fibrils in endothelial cells,
lack of fenestration of endothelial cells. (All this indicates a large exchange between blood and tissues).
the diameter of the capillaries is 7 microns, that is, the capillaries of the gums are true capillaries.
in the marginal gingiva, the capillaries look like capillary loops (“hairpins”) arranged in regular rows.
in the alveolar gum and transitional fold there are arterioles, arteries, venules, veins, arterio-venular anastomoses.
Blood flow intensity in the gums is 70% of the blood flow intensity of all periodontal tissues.
The partial pressure of oxygen in the capillaries of the gums is 35-42 mm Hg. The gingival mucosa also contains non-functioning capillaries, which contain only blood plasma and do not contain red blood cells. These are the so-called plasma capillaries.
Features of blood flow in the region of the periodontal sulcus.
In the region of the gingival sulcus, the vessels do not form capillary loops, but are arranged in a flat layer, being postcapillary venules, the walls of which have increased permeability, through them there is an extravasation of blood plasma and its transformation into gum fluid. Gingival fluid contains substances that provide local immune protection of the oral mucosa.
Local immunity of the oral cavity is a complex multi-component system, including specific and non-specific components, humoral and cellular factors that protect oral and periodontal tissues from microbial aggression.
Humoral factors of local immunity of the oral cavity:
lysozyme- causes depolymerization of polysaccharides of the cell wall of microorganisms;
lactoperoxidase- forms aldehydes, which have a bactericidal effect;
lactoferrin- competes with bacteria for iron, providing a bacteriostatic effect;
mucin- promotes adhesion of bacteria to epithelial cells;
β-lysines- act on the cytoplasm of microorganisms, contributing to their autolysis;
immunoglobulins(A, M, G) - get from the blood serum by passive diffusion through the intercellular spaces of the gingival sulcus and through the epithelial cells. The main role is played immunoglobulin A(IgA). The secretory component S c of immunoglobulin A is synthesized by the epithelial cells of the excretory ducts of the salivary glands. Immunoglobulin A binds to the secretory component in the oral fluid and is fixed on epithelial cells, becoming their receptor, and imparts immunospecificity to the epithelial cell. Immunoglobulin A binds to a bacterial cell, thereby preventing bacteria from settling on the surface of the teeth, and reduces the rate of plaque formation.
polymorphonuclear leukocytes- are released as part of the gingival fluid from the gingival sulcus in an inactive state. Neutrophilic leukocytes have special Fc and Cz receptors for connection with the bacterial cell. Leukocytes are activated in conjunction with antibodies, complement, lactoferrin, lysozyme, peroxidase.
monocytes (macrophages)- phagocytize oral microorganisms, secrete substances that stimulate leukocytes.
epithelial cells gum mucosa - have special Fc and Cz receptors for connection with a microbial cell.
mucin saliva - promotes adhesion of microbial cells and fungi to the surface of the epithelial cell. Constant peeling epithelial cells with microorganisms blocked on them promotes the removal of microbes from the body and prevents them from entering the gingival sulcus and deeper into the periodontal tissue.
Nerve fibers gums (myelinated and unmyelinated) are located in the connective tissue of the lamina propria.
Nerve endings
free- interoreceptors (tissue),
encapsulated(balls), which with age turn into small loops. These are sensitive receptors (which respond to 2 types of stimuli - pain and temperature) - the so-called polymodal receptors. These receptors have a low threshold of irritation, which goes to poorly adapting neurons of the nuclei of the V pair (trigeminal nerve). Sensory receptors respond to pre-pain irritation. The greatest number of these receptors is located in the marginal zone of the gums.
The bone tissue of the alveoli consists of the outer and inner cortical plates and the spongy substance located between them. The spongy substance consists of cells separated by bone trabeculae, the space between the trabeculae is filled with bone marrow (red bone marrow - in children and young men, yellow bone marrow - in adults). A compact bone is formed by bone plates with a system of osteons, permeated with channels for blood vessels and nerves.
Direction of bone trabeculae depends on the direction of action of the mechanical load on the teeth and jaws during chewing. Bone of the lower jaw has a fine-mesh structure with predominantly horizontal the direction of the trabeculae. Bone top jaws has a large-celled structure with predominantly vertical the direction of the bony trabeculae. Normal bone function determined by the activities of the following cellular elements: osteoblasts, osteoclasts, osteocytes under the regulatory influence of the nervous system, parathyroid hormones (parathormone).
The roots of the teeth are fixed in the alveoli. The outer and inner walls of the alveoli consist of two layers of compact substance. The linear dimensions of the alveoli are less than the length of the tooth root, therefore the edge of the alveolus does not reach the enamel-cement joint by 1 mm, and the tip of the tooth root does not adhere tightly to the bottom of the alveolus due to the presence of periodontium.
Periosteum covers the cortical plates of the alveolar arches. The periosteum is a dense connective tissue, contains many blood vessels and nerves, and is involved in bone tissue regeneration.
The chemical composition of bone tissue:
1) mineral salts - 60-70% (mainly hydroxyapatite);
2) organic matter - 30-40% (collagen);
3) water - in a small amount.
The processes of remineralization and demineralization in bone tissue are dynamically balanced, regulated by parathyroid hormone (parathyroid hormone), thyrocalcitonin (thyroid hormone) and fluorine also have an effect.
Features of the blood supply to the bone tissue of the jaws.
The blood supply to the bone tissue of the jaws has a high degree of reliability due to collateral blood supply, which can provide 50-70% of pulsed blood flow, and another 20% from the masticatory muscles enters the jaw bone tissue through the periosteum.
Small vessels and capillaries are located in the rigid walls of the Haversian canals, which prevents a rapid change in their lumen. Therefore, the blood supply to the bone tissue and its metabolic activity are very high, especially during the period of bone tissue growth and fracture healing. In parallel, there is also a blood supply to the bone marrow, which performs a hematopoietic function.
Bone marrow vessels have wide sinuses with slow blood flow due to the large cross-sectional area of the sinus. The walls of the sinus are very thin and partially absent, the capillary lumens are in wide contact with the extravascular space, which creates good conditions for the free exchange of plasma and cells (erythrocytes, leukocytes).
There are many anastomoses through the periosteum with periodontium and gingival mucosa. The blood flow in the bone tissue provides nutrition to the cells and the transport of minerals to them.
The intensity of blood flow in the bones of the jaws is 5-6 times higher than the intensity in other bones of the skeleton. On the working side of the jaw, the blood flow is 10-30% greater than on the non-working side of the jaw.
The vessels of the jaws have their own myogenic tone to regulate blood flow in the bone tissue.
Nerve vasomotor fibers run along the blood vessels to regulate the lumen of the vessels by changing the tonic tension of smooth muscles. To maintain the normal tonic tension of the vessels, 1-2 impulses per second go from the cerebral cortex.
Innervation of the vessels of the lower jaw carried out by sympathetic vasoconstrictor fibers from the upper cervical sympathetic ganglion. The vascular tone of the lower jaw can quickly and significantly change when the lower jaw moves during chewing.
Innervation of the vessels of the upper jaw carried out by parasympathetic vasodilating fibers of the nuclei of the trigeminal nerve from the Gasser ganglion.
The vessels of the upper and lower jaws can simultaneously be in various functional states(vasoconstriction and vasodilation). The vessels of the jaws are very sensitive to the mediator of the sympathetic nervous system - adrenaline. Due to this, the vascular system of the jaws has shunting properties, that is, it has the ability to quickly redistribute blood flow using arterio-venular anastomoses. The shunting mechanism is activated during sudden changes in temperature (during meals), which is a protection for periodontal tissues.
PERIODONTIUM(desmodont, periodontal ligament) is a tissue complex located between the inner compact plate of the alveolus and the cementum of the tooth root. The periodontium is a formed connective tissue.
Periodontal gap width is 0.15-0.35 mm. The shape of the periodontal gap is “hourglass” (there is a narrowing in the middle part of the root of the tooth), which gives the root greater freedom to move in the cervical third of the periodontal gap and even more in the apical third of the periodontal gap.
Composition of periodontium. The periodontium consists of:
fibers (collagen, elastic, reticulin, oxytalan);
cells,
intercellular ground substance of connective tissue.
Allocate 4 zones of periodontal fibers:
in the cervical region - the horizontal direction of the fibers,
in the middle part of the root of the tooth - an oblique direction of the fibers, the tooth is, as it were, suspended in the alveolus,
in the apical region - the vertical direction of the fibers,
in the apical region - the vertical direction of the fibers.
Periodontal cells:
fibroblasts- participate in the formation and breakdown of collagen fibers that are part of the main substance of the connective tissue.
histiocytes,
mast cells,
plasma cells(perform the function of immune defense of tissues),
osteoblasts(synthesize bone tissue)
osteoclasts(involved in bone resorption)
cementoblasts(participate in the formation of cement),
epithelial cells(the remnants of the tooth-forming epithelium - the islets of Malasse - under the influence of pathogenic factors, cysts, granulomas, and tumors supposedly can form from them);
mesenchymal cells- (poorly differentiated cells, from which various connective tissue cells and blood cells can be formed).
Normally, the root of a tooth has inclined position in the alveolus at an angle of 10 o. Under the action of a force at an angle of 10 about to the longitudinal axis of the tooth, there is a uniform distribution of stresses throughout the periodontium.
At increasing the angle of inclination tooth up to 40 about increases the stress in the marginal periodontium on the pressure side. The elasticity of collagen fibers and their inclined position in the periodontium contribute to the return of the tooth to its original position after the chewing load is removed. Physiological tooth mobility is 0.01 mm.
Features of the periodontal blood supply.
Periodontal vessels are glomerular in nature, located in the niches of the bone wall of the alveoli. The capillary network runs parallel to the surface of the tooth root. There are a large number of anastomoses between periodontal vessels and vessels of bone tissue, gums, bone marrow, which contributes to the rapid redistribution of blood during compression of the periodontal vessels between the root of the tooth and the wall of the alveolus during masticatory pressure. When the periodontal vessels are compressed, foci of ischemia. After the chewing load is removed and ischemia is eliminated, reactive hyperemia, which is small and short, which helps the tooth return to its original position.
With an inclined position of the tooth root in the alveolus at an angle of 10 about when chewing in the periodontium, 2 foci of ischemia occur, with opposite localization (one in the cervical region, the other in the apical region). Areas of ischemia occur in various places of the periodontium due to movements of the lower jaw during chewing. After the chewing load is removed, reactive hyperemia occurs in two opposite areas and contributes to the establishment of the tooth in its original position. The outflow of blood is carried out through the intraosseous veins.
Periodontal innervation is carried out from the trigeminal nerve and the upper cervical sympathetic ganglion. In the apical region of the periodontium are mechanoreceptors (baroreceptors) between bundles of collagen fibers. React to touch to the tooth (pressure). Mechanoreceptors are activated in the phase of incomplete jaw closure, providing a reflex chewing process. With very solid food and very strong closure of the dentition, the pain threshold of irritation of the periodontal mechanoreceptors is overcome, and a protective reaction is activated in the form of a sharp opening of the mouth due to inhibition of sending impulses to the masticatory muscles (periodontitis-muscular reflex is suppressed).
Cement- hard tissue of mesenchymal origin. Covers the root of the tooth from the neck to the top. Provides attachment of periodontal fibers to the root of the tooth. The structure of the cement resembles coarse fibrous bone tissue. Cement consists of a base substance impregnated with calcium salts and collagen fibers. The thickness of the cement in the region of the neck of the tooth is 0.015 mm, in the region of the middle part of the root of the tooth - 0.02 mm.
Types of cement:
primary, acellular- Formed prior to tooth eruption. Covers 2/3 of the length of the root dentin in the cervical area. The primary cement consists of the ground substance and bundles of collagen fibers running parallel to the axis of the tooth in the radial and tangential directions. The collagen fibers of the cementum continue into the Sharpei fibers of the periodontium and the collagen fibers of the bone tissue of the alveoli.
secondary, cellular- is formed after the eruption of the tooth when the tooth enters into occlusion. The secondary cement is layered on the primary cement, covers the dentin in the apical third of the tooth root and the inter-root surface of multi-rooted teeth. The formation of secondary cement continues throughout life. The new cement is layered on top of the existing cement. Cells involved in the formation of secondary cementum cementoblasts. The surface of the cement is covered with a thin, not yet calcified cementoid layer.
collagen fibers,
adhesive base material
cells cementoblasts- process cells of a stellate shape, located in the cavities of the main substance of the cement in individual lacunae. With the help of a network of tubules and processes, the cementoblasts are connected with each other and with the dentinal tubules, through which the diffusion of nutrients from the periodontium is carried out. Cement has no blood vessels and nerve endings. The thickness of the secondary cement in the area of the neck of the tooth is 20-50 microns, in the area of the root apex - 150-250 microns.
Questions of test control.
1. Periodontium is:
a) tooth, gum, periodontium. 1 answer
b) tooth, gum, periodontium, alveolar bone.
c) tooth, gum, periodontium, alveolar bone, root cementum.
2. Alveolar gum is:
b) gum surrounding the tooth 1 answer
3. Marginal gum is:
a) gingival papilla and gum around the tooth.
b) the gum surrounding the tooth. 1 answer
c) gum covering the alveolar process.
4. Normally, the epithelium does not keratinize:
a) gingival sulcus.
b) papillary gums. 1 answer
c) alveolar gums.
5. Alveolar gum consists of:
a) epithelium and periosteum.
b) epithelium and mucosa proper 1 answer
c) epithelium, proper mucosal and submucosal layers.
6. With intact periodontium, the gingival sulcus contains:
a) microbial associations.
b) exudate. 1 answer
c) gingival fluid.
d) granulation tissue.
7. With intact periodontium, the gingival sulcus is determined:
a) clinically.
b) histologically. 1 answer
c) X-ray.
Independent work of students.
Students receive patients with periodontal diseases, examine the gums, identify gum zones and determine the presence of a normal state or pathological changes in periodontal tissues. It is necessary to correctly determine the zones of the gums, determine the color of the gums, the presence or absence of edema of the mucous membrane of the gums, determine the depth of the gingival sulcus and the integrity of the dentogingival attachment.
Answers to test control questions:
1b, 2c, 3b, 4a, 5b, 6c, 7c.
Main literature.
1. Borovsky E.V. Therapeutic dentistry. M.: Techlit.-2006.-554s.
2. Danilevsky N.F., Magid E.A., Mukhin N.A. etc. Periodontal diseases. Atlas. M.: Medicine.-1993.-320s.
3. Periodontal diseases edited by prof. L.Yu. Orekhova. M.: Poli-MediaPress.-2004.-432p.
4. Lukinykh L.M. etc. Periodontal disease. Clinic, diagnosis, treatment and prevention. N.Novgorod: NGMA.-2005.-322p.
Additional literature.
1. Ivanov V.S. Periodontal diseases. M.: MIA.-1998.-295s.
2. Balin V.N., Iordanishvili A.K., Kovalevsky A.M. Practical periodontology. St. Fri.: "Peter".-1995.-255p.
3. Loginova N.K., Volozhin A.I. Pathophysiology of the periodontium. Teaching aid. M.-1995.-108s.
4. Kuryakina N.V., Kutepova T.F. Periodontal diseases. M.: Medkniga. N.Novgorod. NGMA.-2000.-159p.
5. Storm A.A. Periodontology - yesterday, today and...// Periodontology.-1996.-№1.-P.26.
6. Straka M. Periodontology–2000. // New in dentistry.-2000. -No. 4.-S.25-55.
7. Kirichuk V.F., Chesnokova N.P. and other Physiology and pathology of the periodontium. Tutorial. Saratov: SGMU.-1996.-58p.
Having a beautiful snow-white smile and good gums is probably the dream of any person. The health and beauty of teeth is directly related to the condition of the periodontium. The collection of tissues located near the alveoli of the tooth and holding it is called the periodontium. Each element of this complex performs its proper function, so the failure of one of them leads to disruption of the overall functioning.
Its main components are:
gum, cell (alveolus) of the tooth, periosteum, tissue, periodontium and tooth.
- gums- a constituent tissue of the mucous membrane of the oral cavity, surrounding the alveolar processes of the teeth, protecting their roots from infection and pathogens, and also playing an active role in the operation of the jaw apparatus as a whole. The surface layer of the gums is a keratinized epithelium, therefore it has excellent regeneration.
- Alveolar process of the tooth- a tooth cell that is located in the periosteum of the jaw. It consists of the inner (lingual) and outer (buccal) walls and a spongy element (substance). The alveoli are located separately from each other and are separated by bone plates. The buccal and lingual walls of the alveolus consist of a compact substance and form cortical plates of the alveolar processes, the upper layer of which is covered with the periosteum. On the side of the tongue, the cortical plates are much thicker than on the side of the cheek. Alveoli changes throughout life, this is due to the constant functional load on the teeth.
- Periodontium- is a structural bundle of fibers that help to fix the tooth in its cell. Its main component is collagen fibrous tissue, which is a kind of connecting link between the cement of the tooth and the alveoli. The periodontium also consists of small blood vessels and nerve endings. Its function is that it helps to soften and change the load on the teeth.
- Tooth consisting of enamel, cementum, dentin, pulp and root. Each element of the tooth perform its function . Cement- a substance resembling bone in its composition, and covering the neck and root of the tooth. Due to it, the tooth is very tightly held in the alveolus. . Tooth enamel It is a dense shell that covers the crown of the tooth. It is the hardest tissue found in the human body. It protects the tooth from premature decay and damage. Dentine- one of the main components of the periodontium and is a mineralized fibrous tissue, covered with a layer of cement and enamel. Dentin is stronger than bone but softer than enamel. Serves as a protective element. dental pulp- soft connective tissue, consisting of blood vessels and nerves, the main function of which is to nourish and saturate the tooth with nutrients.
The main functions of the periodontium include
It follows that the functions of the periodontium determine each other, help maintain a balance between the external and internal spheres, thereby maintaining and protecting its healthy state. If one or another function is violated, a failure begins in its entire structure.
Diagnostics and treatment of periodontal diseases
periodontal disease- one of the most common diseases in dentistry, characterized by the defeat of its main elements. They affect about 80% of the population. The periodontium is the first to take on the negative impact of pathogens.
Causes of painful periodontal conditions
The course of periodontal disease may have a dystrophic, tumor-like and, the most common inflammatory character.
Diagnostics
The variety of types of periodontal diseases, their relationship with other pathological changes in the functioning of the body as a whole have led to the fact that the issue of diagnosing them goes beyond the “office” of dentistry. Methods for examining a patient with suspicion of a particular type of disease are divided into:
- The main ones include a visual examination of the oral cavity and questioning the patient for associated signs and symptoms.
- Additional - the use of medical equipment in making an accurate diagnosis: x-rays, tests.
A very good answer when making a diagnosis is given by an index analysis of the state of periodontal tissue. That is, a special list is compiled, where the dentist, using a five-point system, notes the state of the periodontal structure. This allows you to observe the dynamics of changes in tissues over a long period of time and see the result of the treatment: whether there are positive changes or not.
Treatment of periodontal diseases
Based on the type and severity of the disease, the dentist prescribes adequate treatment. Periodontal treatment directed to eliminate the causes of the disease and improve the state of the functions of the elements that make up the structure of the periodontium. When prescribing therapy, the general condition of the patient and his thorough examination are important. A successful result in the elimination of the disease depends not only on the measures taken by the doctor, but also on the patient himself, who must comply with the treatment plan prescribed by the dentist.
To drugs in the fight against periodontal diseases are divided into the following groups:
- Antibacterial drugs: antibiotics, sulfanilamide, antifungal and antiseptic drugs;
- Anti-inflammatory drugs;
- Preparations that strengthen the general condition of the patient: multivitamins, immunostimulants, etc.
In the presence of tumor-like diseases, the patient may need surgery to remove overgrown tissues.
With periodontal disease therapy is carried out only to eliminate the symptoms, but not the disease itself: at the moment there is no treatment for this type, because the root cause of its appearance has not been identified. In this case, the dentist prescribes treatment aimed at reducing sensitivity and possible inflammatory processes. This can be a finger massage of the gums, using therapeutic pastes and physiotherapy, using high-frequency current.
Preventive measures for periodontal disease
In order for the tissue and structure of the periodontium to be healthy, it is necessary observe the following preventive measures:
The main thing in prevention is the observance of oral hygiene, because with improper care, pathological processes can occur that will lead to a violation of the functions of the structure of the entire periodontium. Timely treatment will help to avoid serious problems.
In order to perform their main function - crushing and softening food, the formation of a food lump - the teeth must be well strengthened in the jawbone. This is achieved through the whole. The tissues that provide strength for holding teeth in the hole include bones, ligaments, gums, covering the bone tissue of the alveolar process. Together, all tissues hold the tooth tightly in the jaw, and the gums prevent damage by solid particles of food and the penetration of pathogens. Since these anatomical formations perform the same function, medical science has combined them into one common name - the periodontium. Periodental tissues have been studied by physicians for a long time, but the term periodontal was introduced into world scientific circulation only in 1921.
Periodontist
Periodontium: structure and functions
Medical science has united several structural elements with this concept. These include gums, bone tissue, periodontium and dental cement in the root area. All elements are innervated and supplied with blood from one source, which once again proves the unity of tissues.
The periodontium and its functions for the life of the tooth can not be overestimated. Let's name the main ones:
- supporting (it is also shock-absorbing) - tissues fix the tooth in the hole, give functional pressure and regulate pressure during chewing. If the periodontium is affected, then there is a functional overload of the periodontium, threatening the loss of a tooth;
- barrier - the complex acts as an outpost that prevents bacteria and toxic substances from entering the root;
- trophic - ensuring the metabolism of cement;
- reflex - nerve plexuses, glomeruli and endings located in the tissues regulate the force of contraction of the chewing muscles, depending on the type of food being chewed;
- plastic function - consists in the constant renewal of tissue that suffers as a result of physiological and pathological processes.
The anatomy of the periodontium is quite complex. The ectodermal epithelium, as well as the mesenchyme of the oral cavity, take an active part in the formation of this tissue. The epithelium deepens into it and forms the labial and dental plates. As a result, flask-like outgrowths are formed, corresponding in number of teeth. Later they are converted into enamel. The mesenchyme near the outgrowth of the epithelium is transformed into the dental papilla. The formation of pulp and dentin comes from this structure. Together, the connective tissue and the dental papilla form the dental sac. It develops the root cement, the ligamentous apparatus of the tooth and its bone base. Periodontal tissues are formed during the period of histogenesis.
Tissue formation begins from the moment of odontogenesis and lasts until the teeth erupt to the surface. The structure of the periodontium is qualitatively different at different stages of its formation. By this time, the formation of the root, periosteum and bone of the alveolar process is already completed. The formation of tissues of permanent teeth is completed by the age of three. Features of the structure of periodontal tissues in children are thinner and less dense cement, not dense connective tissue, weak mineralization of the alveolar bone. By the age of fourteen in adolescents, the reinforcement of periodontal tissue is completed, and by the age of twenty or thirty, the mineralization of the alveolar bone is completed.
The structure of periodontal tissues is characterized by the inclusion of several functionally distinct formations. So, the structural components of the periodontium are:
The structure of periodontal tissues
- gum - is a covering of the alveolar processes of both jaws. It is tightly pressed in the cervical region. Papillae of the same name are located in the interdental space. It is here that suppurative processes most often begin.
- periodontium - a complex of fibers to secure the tooth in the hole. It is located in the middle between the wall of the alveolus and the cementum of the root, for which it received the second name pericement. The periodontium consists of layers of loose fibrous tissue with bundles, plexuses and glomeruli of nerves, arteries, arterioles and veins, and lymphatic vessels passing through it.
- alveolar process - a depression localized in the jawbone for a tooth. They are present on both jaws according to the number of teeth. Inside, the process outwardly resembles a sponge pierced by channels. The alveolar process is constantly undergoing changes, since the teeth are not always equally loaded. The alveolar gum is closely connected with the process;
- cement - covering the tooth root from the edges of the enamel to its top. In the cervical part of the tooth, cement can be applied to the enamel. The chemical composition is similar to bone - it contains organic matter, water and trace elements;
- Tooth enamel is the hard tissue of the human body. Protects both the neck of the tooth and its crown. Enamel is located above the dentin, its thickness in different parts of the tooth is different - it is thickest in the region of chewing humps, and thinnest in the region of the neck of the tooth. It consists of ninety-five percent minerals, it also has one percent organic matter and four percent water. When damaged, the enamel is not capable of recovery;
- The pulp is a loose fibrous tissue rich in collagen. Localized in the inner part of the tooth. It contains the cellular part, the ground substance, fibers, vessels and nerves. The pulp plays an important role in metabolism, contains a lot of blood vessels - arteries, arterioles and veins. They provide nutrition to the pulp and remove waste products from it;
- Dentin is the second hardest tissue in humans. Seventy percent consists of inorganics. Due to the high elasticity of dentin and its porous structure, the main metabolic processes of the tooth take place in it.
The innervation of the periodontium occurs due to the trigeminal nerve. In the region of the tops of the teeth, nerves form nerve plexuses. In the same apex of the tooth, the nerve branch divides and diverges to the pulp of the tooth and the periodontium. The most nerve-rich part of the periodontium is located in the root region. One of the functions of the nerve endings in the root region is the regulation of the degree of masticatory pressure.
The blood supply to the periodontium is provided by a branch of the maxillary and mandibular arteries, which is a branch of the carotid artery. Vessels, together with lymph, provide nutrition directly to the periodontium and protect it. The pathogenesis of periodontal diseases is determined by the ability of capillaries to permeability and resistance in tissues.
blood supply
As a result of the development of the body, the periodontium also changes. The age characteristics of periodontal disease in children and older people are different, so doctors, based on the knowledge of these features, must correctly diagnose and treat periodontal disease. In each specific clinical case, the effect of stress on the periodontium, the effect of smoking on the periodontium, and other adverse factors are taken into account. Periodontology deals with the treatment of diseases of the periodontal tissues, and the specialist -.
The nursing process for periodontal disease is limited to taking an anamnesis, determining the oral hygiene index, preparing the patient for tests and filling out a medical record for a dental patient.
Tasks of periodontology
Periodontology is a field of dental activity in which narrow-profile doctors (periodontists) are engaged in the treatment of diseases of the periodontal tissues. Since this concept is broad, the tasks of periodontology are quite diverse. Periodontology not only studies the pathology of the gums, as many people think, but also deals with pathologies of the root of the tooth, ligaments, and much more. The objectives of periodontology are as follows:
- study of the origin and pathological changes of the periodontium;
- diagnosis and treatment of diseases;
- study of complications and methods for their elimination.
Types of periodontal diseases
Periodontal tissue disease occurs in eighty percent of the population. The etiology and pathogenesis of periodontal diseases lie in inflammatory and degenerative processes. In the differential diagnosis of ailments, it is necessary to distinguish between syndromes that manifest themselves in periodontal tissues. In such cases, the underlying disease is treated, and diseases of the periodontal tissues are treated according to the symptomatic principle.
Inflammation of the periodontium in medicine is called periodontitis, and dystrophy - periodontal disease. Periodontitis, in turn, is divided into generalized, systemic and local. Often, periodontitis and periodontitis occur together, which complicates the treatment of the disease.
Inflammatory periodontal disease is as follows:
- gingivitis - gum inflammation as a result of the influence of adverse factors;
- atrophic changes in the gums - a disease characterized by degenerative processes in the gums and exposure of the teeth;
- chronic periodontitis - inflammation of tissues with the destruction of its structures up to the bone tissue.
In order to prevent periodontal and oral mucosa diseases, prevention of periodontal diseases is important. Doctors advise to carry it out at all stages of a person's life, and start even in the prenatal period.
Prevention of periodontal disease in mother and child is as follows:
- regulation of the nutrition of a pregnant woman;
- sanitation of the oral cavity;
- treatment of somatic diseases;
- breastfeeding in infancy;
- rational nutrition of the child according to his age;
- prevention of infectious diseases;
- correct mode of work and rest;
- regular check-ups at the dentist;
- anticarious measures.
Therapeutic and preventive measures carried out in dental clinics include a range of services, the use of which will help to avoid periodontal diseases. These services include:
- sanitation of the oral cavity;
- removal of plaque and tartar;
- treatment of congenital and acquired dental anomalies;
- anti-carious measures;
- treatment of other pathologies of the oral cavity.
Periodontist is a complex of tissues surrounding the tooth, constituting a single whole, having a genetic and functional commonality.
The term "periodontium" comes from the Greek words: raga - around, around; and odontos - tooth.
Tissues that make up the periodontium:
- gum,
- bone tissue of the alveoli (together with the periosteum),
- periodontium,
- tooth (cement, root dentin, pulp).
When a tooth is lost or extracted, the entire periodontium is resorbed.
gum structure
Gum- mucous membrane covering the alveolar processes of the jaws and covering the necks of the teeth. Normally, the mucous membrane of the gums is pale pink in color, its surface is uneven, similar to an orange peel due to small retractions that form at the site of attachment of the gums to the alveolar bone by bundles of collagen fibers. With inflammatory edema, the irregularities of the mucous membrane of the gums disappear, the gum becomes even, smooth, shiny.
gum zones:
- marginal gingiva, or free gingival margin;
- alveolar gum, or attached gum;
- sulcular gum, or gingival sulcus;
- transitional fold.
Marginal gingiva- this is the gum surrounding the tooth, 0.5-1.5 mm wide. Includes interdental, or gingival papilla - papillary gum.
Alveolar gum- this is the gum covering the alveolar process of the jaws, 1-9 mm wide.
Sulcular gingiva (gingival sulcus)- wedge-shaped space between the surface of the tooth and the marginal gum, 0.5-0.7 mm deep.
gingival sulcus lined with striated epithelium, which is attached to the enamel cuticle. The place of attachment of the epithelium to the enamel is called the gingival attachment. Gingival Attachment considered as a functional unit consisting of 2 parts:
epithelial attachment, or junctional epithelium, which forms the bottom of the gingival sulcus, is found above the enamel-cement junction on the enamel. The width of the epithelial attachment ranges from 0.71 to 1.35 mm (average 1 mm);
connective tissue fibrous attachment, which is at the level of the enamel-cement joint on the cement. The width of the connective tissue attachment ranges from 1.0 to 1.7 mm (average 1 mm).
For physiological attachment of the gingiva to the tooth and for a healthy periodontium, the gingival attachment must be at least 2 mm wide. This dimension is defined as the biological width of the gingiva.
Depth of the anatomical gingival sulcus less than 0.5 mm, determined only histologically.
Clinical gingival sulcus a depth of 1-2 mm is determined by probing.
The epithelial attachment is weak and can be destroyed by probing or working with other instruments. For this reason, the clinical depth of the gingival sulcus is greater than the anatomical depth. Disruption of the connection between the attachment epithelium and the enamel cuticle indicates the beginning of the formation of a periodontal pocket.
Histological structure of the gums.
Histologically, the gum consists of 2 layers:
Stratified squamous epithelium,
Own plate of the mucous membrane of the gums (lamina propria).
There is no submucosal layer.
The structure of the stratified squamous epithelium of the oral cavity:
basal layer- consists of cylindrical cells located on the basement membrane;
spiny layer- consists of cells of a polygonal shape, which are interconnected with the help of hemidesmosomes;
granular layer- cells are flat, contain grains of keratohyalin;
stratum corneum- cells are flat, without nuclei, keratinized, constantly desquamated.
The basal layer is basement membrane which separates the epithelium from the lamina propria of the gingival mucosa.
In the cytoplasm of cells of all layers of the epithelium, except for the stratum corneum, there are a large number of tonofilaments. They determine the turgor of the gums, which resists the mechanical load on the mucous membrane and determines its extensibility. The epithelium of the marginal gums is keratinized, which makes it more resistant to mechanical, thermal and chemical influences during meals.
Between the cells of the stratified squamous epithelium is the gluing basic substance of the connective tissue (matrix), which includes glycosaminoglycans (including hyaluronic acid). Hyaluronidase (microbial and tissue) causes depolymerization of glycosaminoglycans of the main substance of the connective tissue, destroying the bond of hyaluronic acid with the protein, as a result of which the hyaluronic acid molecule changes its spatial configuration, pores form and the permeability of the connective tissue increases for various substances, including microbes and their toxins. .
Histological structure of the attachment epithelium.
The epithelium of the attachment consists of several (15-20) rows of oblong cells located parallel to the surface of the tooth.
There are no blood vessels and nerve endings in the epithelium of the gingival mucosa.
Histological structure of the lamina propria of the gingival mucosa.
own record- is a connective tissue formation, consists of two layers:
Superficial (papillary),
Deep (mesh).
papillary layer formed by loose connective tissue, the papillae of which protrude into the epithelium. In the papillae are blood vessels and nerves, there are nerve endings.
mesh layer formed by denser connective tissue (contains more fibers).
Connective tissue composition:
The main substance is the intercellular matrix (35%), formed by macromolecules of proteoglycans and glycoproteins. The main glycoprotein is fibronectin, which ensures the connection of the protein with the cellular matrix. Another type of glycoprotein, laminin, provides attachment of epithelial cells to the basement membrane.
fibers(collagen, argyrophilic) - 60-65%. Fibers are synthesized by fibroblasts.
cells(5%) - fibroblasts, polymorphonuclear leukocytes, lymphocytes, macrophages, plasma, mast and epithelial cells.
Blood supply to the mucous membrane of the gums.
The gums are supplied with blood from the subperiosteal vessels, which are the terminal branches of the hyoid, mental, facial, great palatine, infraorbital and posterior superior dental arteries. There are many anastomoses through the periosteum with the vessels of the alveolar bone and periodontium.
Microcirculatory bed of the gums represented by: arteries, arterioles, precapillaries, capillaries, postcapillaries, venules, veins, arteriovenular anastomoses.
Features of the capillaries of the mucous membrane of the gums.
For capillaries of the gingival mucosa characteristic:
The presence of a continuous basement membrane, the presence of fibrils in endothelial cells,
Lack of fenestration of endothelial cells. (All this indicates a large volume exchange between blood and tissues)
The diameter of the capillaries is 7 microns, that is, the capillaries of the gums are true capillaries.
In the marginal gingiva, the capillaries look like capillary loops ("hairpins") arranged in regular rows.
In the alveolar gum and transitional fold there are arterioles, arteries, venules, veins, arterio-venular anastomoses.
Blood flow in the vessels of the gums carried out due to the difference in intravascular pressure. From the arterial capillaries (where the pressure is 35 mmHg) there is a filtration of water, oxygen and nutrients into the tissues (where the pressure is 30 mmHg), and from the tissues there is a filtration of water, carbon dioxide and metabolites into the venules ( where the pressure is only 2 0 mm r t. s t.)
The intensity of blood flow in the gums is 70% of the intensity of blood flow in all periodontal tissues.
The partial pressure of oxygen in the capillaries of the gums is 35-42 mm Hg.
In the gingival mucosa there are also non-functioning capillaries that contain only blood plasma and do not contain red blood cells. These are the so-called plasma capillaries.
Features of blood flow in the periodontal sulcus.
In the region of the gingival sulcus, the vessels do not form capillary loops, but are arranged in a flat layer. These are post-capillary venules, the walls of which have increased permeability, through which there is an extravasation of blood plasma and its transformation into gingival fluid. Gingival fluid contains substances that provide local immune protection of the oral mucosa.
Local immunity of the oral cavity is a complex multicomponent system, including specific and non-specific components, humoral and cellular factors that protect the oral cavity and periodontal tissues from microbial aggression.
Humoral factors of local immunity of the oral cavity:
Lysozyme - causes depolymerization of polysaccharides of the cell membrane of a microorganism;
Lactoperoxidase - forms aldehydes, which have a bactericidal effect;
Lactoferrin competes with bacteria for iron, exerting a bacteriostatic effect;
Mucin - promotes adhesion of bacteria to epithelial cells;
Beta-lysins - act on the cytoplasm of microorganisms, contributing to their autolysis;
Immunoglobulins (A, M, G) - come from the blood serum by passive diffusion through the intercellular spaces of the gingival sulcus and through the epithelial cells. The main role is played by immunoglobulin A (Ig A). The secretory component 5C of immunoglobulin A is synthesized by the epithelial cells of the excretory ducts of the salivary glands. Immunoglobulin A binds to the secretory component in the oral fluid and is fixed on the epithelial cells, becoming their receptor, giving the epithelial cell immunospecificity. Immunoglobulin A binds to a bacterial cell, preventing bacteria from settling on the surface of the teeth, and reduces the rate of plaque formation.
Cellular factors of local immunity of the oral cavity:
Polymorphonuclear leukocytes - stand out as part of the gingival fluid from the gingival sulcus in an inactive state. Neutrophilic leukocytes have special Fc and C3 receptors for connection with the bacterial cell. Leukocytes are activated in conjunction with antibodies, complement, lactoferrin, lysozyme, peroxidase.
Monocytes (macrophages) - phagocytize oral microorganisms, secrete substances that stimulate leukocytes.
Epithelial cells of the gingival mucosa - have special receptors for connection with a microbial cell.
Saliva mucin promotes adhesion of microbial cells and fungi to the surface of the epithelial cell.
Constant desquamation of epithelial cells with microorganisms blocked on them promotes the removal of microbes from the body and prevents them from entering the gingival sulcus and deeper into the periodontal tissue.
Innervation of the mucous membrane of the gums.
Nerve fibers of the gums(myelinated and unmyelinated) are found in the connective tissue of the gingival lamina propria.
Nerve endings:
Free - interoreceptors (tissue),
Encapsulated (balls), which with age turn into small loops. These are sensitive receptors (pain, temperature) - the so-called polymodal receptors (which respond to 2 types of stimuli). These receptors have a low threshold of irritation, which goes to poorly adapting neurons of the nuclei of the V pair (trigeminal nerve). Sensitive receptors respond to each pain stimulus. The greatest number of these receptors is located in the marginal zone of the gums.
The structure of the bone tissue of the alveoli
The bone tissue of the alveoli consists of the outer and inner cortical plates and the spongy substance located between them. The spongy substance consists of cells separated by bone trabeculae, the space between the trabeculae is filled with bone marrow (red bone marrow in children and young men, yellow bone marrow in adults). A compact bone is formed by bone plates with a system of osteons, permeated with channels for blood vessels and nerves.
The direction of the bone trabeculae depends on the direction of the mechanical load on the teeth and jaw during chewing. The bone of the lower jaw has a fine-mesh structure with a predominantly horizontal direction of the trabeculae. The bone of the upper jaw has a coarse-mesh structure with a predominantly vertical direction of bone trabeculae.
The normal function of bone tissue is determined by the activity of the following cellular elements: osteoblasts, osteoclasts, osteocytes under the regulatory influence of the nervous system, parathyroid hormone (parathormone).
The roots of the teeth are fixed in the alveoli. The outer and inner walls of the alveoli consist of two layers of compact substance. The linear dimensions of the alveoli are less than the length of the tooth root, therefore the edge of the alveolus does not reach the enamel-cement joint by 1 mm, and the tip of the tooth root does not adhere tightly to the bottom of the alveolus due to the presence of periodontium.
The periosteum covers the cortical plates of the alveolar arches. The periosteum is a dense connective tissue, contains many blood vessels and nerves, and is involved in bone tissue regeneration.
The chemical composition of bone tissue:
- mineral salts - 60-70% (mainly hydroxyapatite);
- organic matter - 30-40% (collagen);
- water - in a small amount.
The processes of remineralization and demineralization in bone tissue are dynamically balanced, regulated by parathyroid hormone (parathyroid hormone), thyrocalcitonin (thyroid hormone) and fluorine also have an effect.
Features of the blood supply to the bone tissue of the jaws.
The blood supply to the bone tissue of the jaws has a high degree of reliability due to collateral blood supply, which can provide a pulsed blood flow by 50-70%, and through the periosteum another 20% from the masticatory muscles enters the bone tissue of the jaws.
Small vessels and capillaries are located in the rigid walls of the Haversian canals, which prevents a rapid change in their lumen. Therefore, the blood supply to the bone tissue and its metabolic activity are very high, especially during the period of bone tissue growth and fracture healing. In parallel, there is also a blood supply to the bone marrow, which performs a hematopoietic function.
Bone marrow vessels have wide sinuses with slow blood flow due to the large cross-sectional area of the sinus. The walls of the sinus are very thin and partially absent, the capillary lumens are in wide contact with the extravascular space, which creates good conditions for the free exchange of plasma and cells (erythrocytes, leukocytes).
There are many anastomoses through the periosteum with periodontium and gingival mucosa. The blood flow in the bone tissue provides nutrition to the cells and the transport of minerals to them.
The intensity of blood flow in the jaw bones is 5-6 times higher than the intensity of blood flow in other bones of the skeleton. On the working side of the jaw, the blood flow is 10-30% more than on the non-working side of the jaw.
The vessels of the jaws have their own myogenic tone to regulate blood flow in the bone tissue.
Innervation of the bone tissue of the jaws.
Nerve vasomotor fibers run along the blood vessels to regulate the lumen of the vessels by changing the tonic tension of smooth muscles. To maintain the normal tonic tension of the vessels from the cerebral cortex, 1-2 impulses per second go to them.
The innervation of the vessels of the lower jaw is carried out by sympathetic vasoconstrictor fibers from the upper cervical sympathetic node. The vascular tone of the lower jaw can quickly and significantly change when the lower jaw moves during chewing.
The innervation of the vessels of the upper jaw is carried out by parasympathetic vasodilating fibers of the nuclei of the trigeminal nerve from the gasser node.
The vessels of the upper and lower jaws can simultaneously be in different functional states (vasoconstriction and vasodilation). The vessels of the jaws are very sensitive to the mediator of the sympathetic nervous system - adrenaline. Due to this, the vascular system of the jaws has shunting properties, that is, it has the ability to quickly redistribute blood flow using arterio-venular anastomoses. The shunting mechanism is activated during sudden changes in temperature (during meals), which is a protection for periodontal tissues.
The structure of the periodontium
Periodontium(desmodont, periodontal ligament) is a tissue complex located between the inner compact plate of the alveolus and the cementum of the tooth root. Periodontium is a structured connective tissue.
Width periodontal gap is 0.15-0.35 mm. The form Pperiodontal fissure- "hourglass" (there is a narrowing in the middle part of the tooth root), which gives the root more freedom to move in the cervical third of the periodontal gap and even more in the apical third of the periodontal gap.
Periodontium consists from:
Fibers (collagen, elastic, reticulin, oxytalan);
Intercellular ground substance of connective tissue.
Collagen fibers of the periodontium are arranged in the form of bundles, woven on one side into the cementum of the tooth root, and on the other side into the bone tissue of the alveoli. The course and direction of periodontal fibers is determined by the functional load on the tooth. The fiber bundles are oriented in such a way as to prevent the tooth from moving out of the alveolus.
Allocate 4 zones of periodontal fibers:
In the cervical region - the horizontal direction of the fibers,
In the middle part of the root of the tooth - an oblique direction of the fibers, the tooth is, as it were, suspended in the alveolus),
In the apical region - the horizontal direction of the fibers,
In the apical region - the vertical direction of the fibers.
Collagen fibers are collected in bundles 0.01 mm thick, between which there are layers of loose connective tissue, cells, vessels, nerve receptors.
Periodontal cells:
- fibroblasts- participate in the formation and breakdown of collagen fibers that are part of the main substance of the connective tissue;
- histiocytes,
- mast cells, and plasma cells (perform the function of immune defense of tissues),
- osteoblasts(synthesize bone tissue)
- osteoclasts(involved in bone resorption)
- cementoblasts(participate in the formation of cement),
- epithelial cells(the remnants of the tooth-forming epithelium - the "Islands of Malaise", under the influence of pathogenic factors, cysts, granulomas, tumors supposedly can form from them),
- mesenchymal cells- poorly differentiated cells, from which various connective tissue cells and blood cells can form.
Periodontal collagen fibers have minimal extensibility and compression, which limits the movement of the tooth in the alveolus under the action of forces of masticatory pressure, which leaves 90-136 kg between the molars. Thus, the periodontium is a shock absorber of masticatory pressure.
Normally, the root of the tooth has an inclined position in the alveolus at an angle of 10 °. Under the action of a force at an angle of 10° to the longitudinal axis of the tooth, there is a uniform distribution of - stresses throughout the periodontium.
With an increase in the angle of inclination of the tooth to 40°, the stress in the marginal periodontium on the pressure side increases. The elasticity of collagen fibers and their inclined position in the periodontium contribute to the return of the tooth to its original position after the chewing load is removed.
Physiological tooth mobility is 0.01 mm.
Features of the periodontal blood supply.
Periodontal vessels are glomerular in nature, located in the niches of the bone wall of the alveoli. The capillary network runs parallel to the surface of the tooth root. There are a large number of anastomoses between periodontal vessels and vessels of bone tissue, gums, bone marrow, which contributes to the rapid redistribution of blood during compression of periodontal vessels between the root of the tooth and the wall of the alveolus with masticatory pressure. When compression of periodontal vessels occurs ischemia foci. After the chewing load is removed and ischemia is eliminated, reactive hyperemia occurs, which helps the tooth return to its original position.
With an inclined position of the root of the tooth in the alveolus, at an angle of 10 ° when chewing in the periodontium, 2 foci of ischemia appear, opposite to each other (one in the cervical region, the other in the apical region). Areas of ischemia occur in various places of the periodontium due to movements of the lower jaw during chewing. After the chewing load is removed, reactive hyperemia occurs in two opposite areas and contributes to the establishment of the tooth in its original position. The outflow of blood is carried out through the intraosseous veins.
Periodontal innervation is carried out from the trigeminal nerve and the upper cervical sympathetic ganglion. In the apical region of the periodontium, there are mechanoreceptors (baroreceptors) between bundles of collagen fibers. They respond to touch to the tooth (pressure). Mechanoreceptors are activated in the phase of incomplete jaw closure, providing a reflex chewing process. With very hard food and a very strong closure of the dentition, the pain threshold of irritation of the periodontal mechanoreceptors is overcome and a protective reaction is activated in the form of a sharp opening of the mouth due to inhibition of sending impulses to the masticatory muscles (the periodontitis-muscular reflex is suppressed).
The structure of cement
Cement- hard tissue of mesenchymal origin. Covers the root of the tooth from the neck to the top and provides attachment of periodontal fibers to the root of the tooth. The structure of the cement resembles coarse fibrous bone tissue. Cement consists of a base substance impregnated with calcium salts and collagen fibers.
Types of cement:
primary, acellular- is formed before the eruption of the tooth. Covers 2/3 of the length of the root dentin in the cervical area. The primary cement consists of the base substance and bundles of collagen fibers running parallel to the axis of the tooth in the radial and tangential directions. The collagen fibers of the cementum continue into the Sharpei fibers of the periodontium and the collagen fibers of the bone tissue of the alveoli. The thickness of the primary cement in the area of the neck of the tooth is 0.015 mm, in the area of the middle part of the root of the tooth - 0.02 mm.
secondary, cellular- formed after the eruption of the tooth when the tooth enters into occlusion. The secondary cement is layered on the primary cement, covers the dentin in the apical third of the tooth root and the inter-root surface of multi-rooted teeth. The formation of secondary cement continues throughout life. The new cement is layered on top of the existing cement. Cementoblast cells are involved in the formation of secondary cement. The surface of the cement is covered with a thin, not yet calcified cementoid layer.
Composition of secondary cement:
collagen fibers,
adhesive base material
Cementoblast cells are stellate process cells located in the cavities of the main substance of the cement in individual lacunae. With the help of a network of tubules and processes, the cementoblasts are connected with each other and with the dentinal tubules, through which the diffusion of nutrients from the periodontium is carried out. Cement does not have blood vessels and nerve endings. The thickness of the secondary cement in the area of the neck of the tooth is 20-50 microns, in the area of the root apex - 150-250 microns.
The periodontium is constantly exposed to external (environmental) and internal factors. Sometimes these loads are so strong that the periodontal tissues experience an exceptionally large overload, but at the same time they are not damaged. This is due to the fact that throughout life, the periodontium constantly adapts to new conditions. Examples are the eruption of temporary and permanent teeth, the removal of a tooth from a bite, a change in the nature of food, a disease of the body, trauma, etc. The preservation of normal periodontal function indicates its great adaptive capabilities.
The periodontium is responsible for barrier, trophic functions; provides reflex regulation of masticatory pressure; performs a plastic and shock-absorbing role. It tolerates significant physical overload, is resistant to infection, intoxication, etc.
barrier function periodontal disease is possible subject to the integrity of the periodontium and is provided by the following factors:
The ability of the gingival epithelium to keratinize (with periodontal disease, this ability is impaired);
A large number and special orientation of bundles of collagen fibers;
Turgor of the gums;
The state of GAGs in periodontal connective tissue formations;
Features of the structure and function of the physiological gingival pocket;
The antibacterial function of saliva due to the presence in it of such biologically active substances as lysozyme, lactoferrin, mucin, as well as enzymes, immunoglobulins, polymorphonuclear leukocytes (humoral factors of local protection);
The presence of mast and plasma cells, which play an important role in the production of autoantibodies;
The composition of the gingival fluid containing bactericidal substances and immunoglobulins.
Peroxidases also have a protective effect due to their participation in the regulation of osteoclastic bone resorption and the activity of lysosomal enzymes. The main source of human saliva peroxidase is the small salivary glands of the oral mucosa. Protective factors include cyclic nucleotides (ATP, ADP, AMP), which control inflammatory and immune responses and are involved in maintaining homeostasis (Fedorov, 1981).
The implementation of the barrier function helps to prevent sensitization of the body during odontogenic infection.
Local immunity is provided by a complex multicomponent system that includes humoral, cellular, specific and nonspecific factors (Loginova, Volozhin, 1994). The cellular factors of local periodontal protection (cellular immunity) include T- and B-lymphocytes, neutrophils, macrophages, and mast cells.
Trophic function considered as one of the main functions of the periodontium. Its implementation is ensured by a widely branched network of capillaries and nerve receptors. This function largely depends on the preservation of normal microcirculation in the functioning periodontium.
Reflex regulation of masticatory pressure It is carried out thanks to the numerous nerve endings located in the periodontium - receptors, the irritation of which is transmitted through a wide variety of reflex highways. I. S. Rubinov (1952) showed the transmission scheme of one of the reflexes - periodontal-muscular, which regulates the force of contraction of the chewing muscles (chewing pressure) depending on the nature of the food and the state of periodontal nerve receptors.
plastic function periodontal is the constant reconstruction of its tissues lost during physiological or pathological processes. The implementation of this function occurs due to the activity of cemento- and osteoblasts. A certain role is also played by other cellular elements - fibroblasts, mast cells, as well as the state of transcapillary metabolism.
damping function perform collagen and elastic fibers. The periodontal ligament protects the tissues of the dental alveoli during chewing, and in case of injury, the periodontal vessels and nerves. The depreciation mechanism involves the liquid and colloidal part of interstitial crevices and cells, a as well as changes in vascular metabolism.
All functions of the periodontium, interdependent each other, provide a physiological balance between the external and internal environment of the body, thereby contributing to the preservation of the morphological structure.
